Gripper for yarn carriers and the like

ABSTRACT

A gripper, installed on a gripper carrier, for gripping a yarn carrier (spool, bobbin and the like) is provided with a substantially rigid downwardly extending wall member having an exterior surface. The wall member is fixedly connected to a gripper carrier. The wall member, with a hollow element expandable under fluid pressure, can be inserted into the open interior of a yarn carrier. The external surface of the wall member forms a partial region of the circumference of the gripper. The hollow element is positioned adjacent the wall member and, in one embodiment, is formed in part by the wall member. Upon expansion of the hollow member under fluid pressure, the exterior surface of the wall and at least portions of the hollow member contact the interior surface of the yarn carrier.

United States Patent l l Klein GRIPPER FOR YARN CARRIERS AND THE LIKE [75] Inventor: Konrad Klein, Ebersbach-Sulpach,

Germany [73] Assignee: Zinser-Textilmaschinen GmbH,

Postfach, Germany 221 Filed: Apr. 30, 1973 [2]] Appl. No.: 355,873

[52] US. Cl. 57/52, 294/93 [51] Int. Cl D01h 9/00, B66c 1/46 [58] Field of Search 57/52, 53; 294/93, 99 R,

[56] References Cited UNITED STATES PATENTS 3,367,098 2/1968 Schulz .Q 57/52 3,462,934 8/1969 Schulz et al. 57/52 3,714,770 2/1973 Rothke 57/52 Sept. 17, 1974 Primary Examiner-John Petrakes Attorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT A gripper, installed on a gripper carrier, for gripping a yarn carrier (spool, bobbin and the like) is provided with a substantially rigid downwardly extending wall member having an exterior surface. The wall member is fixedly connected to a gripper carrier. The wall member, with a hollow element expandable under fluid pressure, can be inserted into the open interior of a yarn carrier. The external surface of the wall member forms a partial region of the circumference of the gripper. The hollow element is positioned adjacent the wall member and, in one embodiment, is formed in part by the wall member. Upon expansion of the hollow member under fluid pressure, the exterior surface of the wall and at least portions of the hollow member contact the interior surface of the yarn carrier.

10 Claims, 4 Drawing Figures I GRIPPER FOR YARN CARRIERS AND THE LIKE BACKGROUND OF THE INVENTION This invention concerns a yarn carrier gripping arrangement which includes at least one gripper, disposed on a gripper carrier, for internally gripping a yarn carrier (spool, bobbin and the like). The invention relates more particularly to such a gripper having a hollow element which is expandable by means of fluid pressure, the fluid being conductible into it's hollow interior.

A known gripper is provided with a bag-like bellows made of rubber or synthetic material which, in its pressure-free state, is introducible into the interior of a yarn carrier, and which is expandable by the introduction of fluid under pressure into its hollow interior until it firmly presses against the interior wall of the yarn carrier. A serious disadvantage of this known arrangement exists because the yarn carrier, held by the gripper, can be deviated from its normal position by lateral forces, as a result of the flexibility of the bellows. For example, the lateral pull exerted by an untorn thread of the yarn package located on the yarn carrier can cause considerable undesirable lateral movement; this can lead to damage of the bellows and to the collision of the yarn carrier with machine parts during its movement from one station to the other.

Those yarn carrier gripping arrangements to which the present invention pertains are preferentially employed in automatic yarn carrier changing apparatuses in which the filled-up yarn carriers located on spindles are automatically exchanged for empty spools. In order to avoid the operational disadvantages of the kind mentioned above, it is desired that the yarn carrier gripped by the gripper be designed so that it cannot, to any substantial extent, deviate from its normal position in re-.

sponse to lateral forces. In order to limit the deviation due to lateral forces of a yarn carrier gripped by the gripper, it is known to equip the bag-like bellows with internal longitudinal ribs which increase its lateral stiffness or to dispose a rigid body in the interior of the bellows. These measures, however, are not sufficient in many instances. It is also known to equip the bag-like bellows of such a gripper with a corset, which, however, only limits the expansion of the bellows to prevent its rupture when it is subjected to the pressure of fluid when it is not positioned in the interior of a yarn carrier.

SUMMARY OF THE INVENTION It is the principal object of the present invention to I provide a gripper of the previously-mentioned kind which has high lateral stiffness without incurring a limitation of its gripping function.

The foregoing object, as well as others which are to become apparent from the text which follows, is accomplished in an apparatus which includes at least one gripper, having a circumference, installed on a gripper carrier. The gripper is designed for internally gripping a yarn carrier (spool, bobbin and the like) having an open interior defining an interior surface. The gripper includes a hollow element expandable under fluid pressure. Means are provided for conducting fluid under pressure into the hollow element. The gripper has, as a part thereof, a substantially rigid downwardly extending wall member which has an exterior surface. The

wall member is fixed to the gripper carrier. The wall member and the hollow element, which is positioned adjacent the wall member, can be simultaneously introduced into the open interior of the yarn carrier. The external surface of the wall member forms a partial region of the circumference of the gripper.

In operation, the gripper is first introduced into the interior of a yarn carrier and the hollow member is thereafter supplied with fluid under pressure. As a result, the exterior surface of the wall member and at least portions of the hollow member contact the interior surface of the yarn carrier.

It is a salient feature of the present invention that an external region of the improved gripper, which extends over a partial region of the circumference of the gripper, consists of a rigid wall member immovably connected to the gripper carrier. This wall member extends preferentially over the length of the gripper and is introducible into the interior of a yarn carrier.

The improved gripper can be introduced into yarn supports, such as spools, bobbins and the like, just as can the bag-like grippers of the prior art. The hollow element of the improved gripper then is expanded using fluid under pressure, until it presses firmly against the interior wall of the yarn carrier. This expansion results in pressing the yarn support positively against the exterior surface of the rigid wall member of the gripper. Since this rigid wall member is connected immovably with the carrier holding the gripper, it will hold the yarn support immovably in its intended normal position relative to this carrier against very high lateral forces. In addition, the gripper is compact, operationally safe, and grips the yarn support effectively.

The rigid wall member does not increase constructional costs of the gripper because it can be a formed metallic part which can be very inexpensively produced. In addition, the rigid wall member makes it possible that the hollow element of the gripper can, at least in some places, have a thinner wall than the expandable bag-like members in known grippers, because the hollow element can have a lower lateral stiffness than these known bag-like members. However, it can be provided advantageously, in the novel gripper according to the present invention, for an increase in the lateral stiffness of its flexible wall. This can be accomplished by providing that the flexible wall of the hollow element of the gripper have at least a thickening in the longitudinal direction to which thinner wall sections connect in the circumferential direction.

The rigid wall member of the gripper can suitably exhibit an external profile which is matched to the region of the interior wall of the yarn carrier with which it is tomake contact. In general, this interior wall of such yarn carriers is circular and, correspondingly, the exterior area of the wall member which comes in contact with the yarn carrier can be curved in the shape of a circular arc and can have a radius which is approximately the radius of the corresponding region of the interior wall of the yarn carrier. It can be suitably provided that the rigid wall member of the gripper have the form of a half shell or the like and preferably a uniform thickness.

The rigid wall member and the flexible wall of the hollow element can both extend preferably from the upper to the lower end of the gripper; however, in some cases different lengths can be provided.

In general, it is suitable to construct the rigid wall member as a one-piece shell. However, other embodiments are conceivable. For example, the rigid wall member could have a cross section in the form of a segment of a circle throughout its length and/or would be multipartite. The rigid wall could have apertures or the like therein; for example, it could be constructed in the form of a rigid grid.

In order to make the frictional force between the rigid wall and the yarn carrier as large as possible, the external surface of the rigid wall can be provided with a covering having a high coefficient of friction, or with a knurling, or corrugation, or there could be provided other means, known per se, to achieve as high a coefficient of friction as possible.

In a preferred further embodiment, it is provided that the gripper includes a bag-like bellows, known per se, and that the rigid wall member extends adjacent to the bellows. This arrangement of parts has advantages from the manufacturing point of view and also results in particularly high operational reliability.

In another preferred further embodiment it is provided that the rigid wall member is also a section of wall of the hollow element of the gripper which expands when subjected to fluid under pressure.

In general, for technical reasons, it is especially suitable if the rigid wall member of the gripper has a maximum circumferential extent of substantially half the circumference of the gripper, preferably extending over approximately from about 120 to about 180. However, in some instances it can extend over a smaller or somewhat greater circumferential region. What is important is that there is always a flexible portion of the gripper opposite to the rigid wall member, which portion expands and presses against the interior wall of the yarn carrier located opposite and moves this yarn carrier laterally thereby into a position in which it, too, is pressed against the rigid wall member of the gripper. This lateral displacement of the yarn carrier is, however, only slight so that even if the yarn carrier is disposed on a shaft of a textile spindle, this lateral mobility of the yarn carrier is achieved because of the always present lateral mobility of the shaft of the spindle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partly sectional side elevational view of a gripper associated with a gripper carrier according to the present invention, the visible gripper extending into a yarn carrier, mounted on a spindle, for the purpose of gripping it.

FIG. 2 is a cross-sectional view through the gripper shown in FIG. 1, taken along the sectional line 22.

FIG. 3 is a side elevational view of a gripper according to the second exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view through the gripper shown in FIG. 3, taken along the section line 4-4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, an upper end of a yarn carrier (spool, bobbin or the like), which is not shown in all of its details, is mounted on a partially shown spindle shaft 11 of a spindle forming a portion of a spinning or twisting machine (not shown). The yarn carrier 11 carries a conventional yarn package 12 illustrated by broken lines. The spinning or twisting machine includes, as is well known, a row of such textile spindles on one or both sides of the machine where all the filledup yarn carriers on one row of spindles can be exchanged for empty yarn carriers by means of an automatic yarn carrier changing mechanism which is not shown in all details. For the gripping of the empty and full yarn carriers to be exchanged, the changing mechanism includes a gripper carrier 13 conventionally referred to as a gripper-rail which carries a number of grippers corresponding to the number of spindles in the particular row of spindles involved; one of these grippers 14 is shown in detail in FIG. 1. All of the grippers are identically constructed.

The gripper 14 includes a rigid half-shell-shaped, metallic, downwardly extending wall member 19 and a hollow element in the form of a bag-like bellows 15. The bellows 15, which expands under fluid pressure, is made of rubber or synthetic materialv The bellows 15 is clamped between a flange on the lower end of a threaded stud 16, which is screwed into a threaded bore in the gripper carrier 13, and a metallic hood 17 in a fluid-tight relationship.

The threaded stud 16 has a longitudinal bore so that the interior of bellows 15 communicates with a channel 20 of the gripper carrier serving as a supply line for the fluid under pressure. The bellows 15 is cylindrical over a major portion 22 of its length. As best seen in FIG. 2, the wall of the bellows 15 has a non-uniform thickness and its free end 21 is conical in shape. The rigid wall member 19 is immovably fixedly connected to the gripper carrier 13, for example, by welding it to the hood 17 which, in turn, is held immovably on the gripper carrier 13. The rigid wall member 19 has the cross section ofa portion of a circular arc and forms an exterior wall portion of the gripper 14 by extending laterally adjacent to the bellows 15 where the bellows 15 may lie against it in the pressure-relieved condition or. under certain conditions, it can be located at a small distance from the wall member 19. In a region, designated generally by the numeral 23, the wall member 19 is opposite the cylindrical portion 22 of the bellows l5 and is formed into the shape of a portion of a circular arc so that the radius of its outside surface approximately corresponds to the radius of the opposite interior surface of the yarn carrier 10. The lower portion, designated generally by the numeral 24, of the rigid wall member 19 lies opposite the conical end portion 21 of the bellows 15 and corresponds in shape to this concial end portionv The rigid wall member 19 and the bellows 15 each preferably extends. as shown. over the entire height of the gripper 14. The exterior side of the wall member 19 is provided with a thin frictional coating which is not visible in the drawing. This coating can be made of rubber, for example, and it serves to increase the coefficient of friction of the exterior surface of the wall member 19, thereby establishing an effective frictional contact between the wall member 19 and the yarn carrier 10. The improved frictional contact between the exterior surface of the wall member 19 and the yarn carrier 10 can alternatively be provided by other techniques; for example, by knurling or corrugating the exterior surface of this wall member. The rigid wall member 19 subtends. in the circumferential direction, a central angle of approximately l and forms an exterior region of the gripper 14.

The cross section of the elastic wall of the bag-like bellows 15, which is madeof rubber or synthetic material, is made so that it has a region 26 (FIG. 2) of uniform thickness and in the form of a circular are which conforms to that portion of the inner surface of the rigid wall member 19 which lies opposite to it. To both sides of the region 26 of uniform thickness connect outwardly directed regions 27 which, farther on in the circumferential direction, change into thin-walled regions 29 extending in the circumferential direction to which relatively thicker walled regions 30 connect. The thicker walled regions 30, in turn, are connected by a thin-walled region 31. The gripper 14 is symmetrical with respect to a symmetry plane designated by the numeral 32. The two thick-walled regions 30 increase the lateral stability of the bellows l5 and extend at least over the length of the cylindrical portion 22 of the bellows.

In operation, the gripper 14 can be expanded by means of fluid under pressure, preferably air, if necessary or desirable also by means of some other gas or a liquid, by introducing this fluid under pressure through the channel 20 within the gripper carrier 13 and through the bore in the threaded stud 16 into the hollow interior of the bellows 15. However, when the be]- lows 15 is introduced into yarn carrier or removed from it, the bellows is pressure-relieved. In FIGS. 1 and 2 the gripper 14 is shown in this pressure-relieved condition. In order for the gripper 14 to grip the yarn carrier 10 by frictional contact with it, fluid under pressure is introduced into the bellows 15. As a consequence, the bellows expands by stretching the thin-walled regions 26, 29 and 31 and presses positively both against the inner surface of rigid wall member 19 and against the inner surface of the yarn carrier 10 which lies opposite. As a consequence, a force is exerted on the yarn carrier 10 in the direction of arrow K, which force presses the yarn carrier against the exterior surface of the rigid wall member 19. This motion of the spool is made possible by the fact that the spindle shaft 11 can move laterally to its longitudinal axis a small distance because of the bearings common in such spindles. As a result of the introduction of the fluid under pressure into the bellows 15, the gripper 14 is effectively clamped to the inner surface of the yarn carrier 10 which then can be pulled off the spindle shaft 11 by moving the gripper carrier 13 vertically upward or by moving the spindle 11 downward by means of a motion of a spindle rail (not shown).

Because of the presence of the rigid wall member 19, which is connected immovably to the gripper carrier 13, the gripper 14 is clamped in the yarn carrier 10 and the yarn carrier cannot be undesirably laterally deviated by lateral forces which possibly may be exerted on it during transport, such forces being generated by untorn thread, yarn or the like.

In a further exemplary embodiment of the present invention illustrated in FIGS. 3 and 4, a gripper 14' includes a rigid downwardly extending metallic wall member 19' in the form of a portion of a circular are extending over nearly 180. The wall member 19' is connected immovably, in a manner not shown in further detail in FIGS. 3 and 4, with gripper carrier which can correspond to the gripper carrier 13 (FIG. 1). The gripper 14 also includes an essentially arcuatelyshaped, in cross section, membrane 34 which completes the gripper 14. The membrane 34 is made from rubber or a resilient synthetic material and is connected to the wall member 19 by glue or a similar material to provide a fluid-tight connection so that the gripper l4 defines a rotationally symmetric fluid pressure-responsive element which is hollow inside, is baglike and whose flexible half-wall formed by the membrane 34 is expandable for the clamping of this gripper inside a yarn carrier (not shown in FIGS. 3 and 4) of a similar object. The function of the gripper 14' corresponds essentially to that of the gripper 14 illustrated in FIGS. 1 and 2. The results achieved are the same. The yarn carrier, which is to be carried by the gripper 14, cannot be undesirably, laterally displaced during transport because of the rigid wall member 19.

While the embodiments illustrated in the accompanying drawings and described in the foregoing test are practical adaptations of the present invention, it is to be understood that modifications can be made without departing from the spirit and scope of the invention as defined in the appended claims.

That which is claimed is:

1. In an apparatus having at least one gripper having a circumference, installed on a gripper carrier, for internally gripping a yarn carrier having an open interior defining an interior surface, which gripper includes a hollow element expandable under fluid pressure, and means for conducting fluid under pressure into the hollow element, the improvement comprising: a rigid downwardly extending wall member having an exterior surface, which in an operative position is to contact the interior surface of the yarn carrier, said wall member forming part of said gripper and being fixedly connected to said gripper carrier and which, with said hollow element, can be introduced into the open interior of the yarn carrier, said exterior surface of said wall member forming a partial region of said circumference of said gripper and said hollow element being positioned adjacent said wall member, whereby upon expansion of the hollow member under fluid pressure the exterior surface of the wall member and at least portions of the hollow member may contact the interior surface of the yarn carrier.

2. An arrangement as defined in claim 1, wherein said wall member extends downwardly for substantially the length of said gripper.

3. An arrangement as defined in claim 1, wherein said wall member includes a lowermost portion which extends radially inwardly.

4. An arrangement as defined in claim 3, wherein said lowermost portion of said wall member extends radially inwardly and downwardly.

5. An arrangement as defined in claim 1, wherein said wall member subtends a central angle of from about to about 6. An arrangement as defined in claim 1, wherein said hollow member is a bag-like bellows, said wall member being disposed laterally adjacent said bellows.

7. An arrangement as defined in claim 1, wherein said wall member is integrally connected to a flexible membrane and with said flexible membrane defines at least substantially said hollow element.

8. An arrangement as defined in claim 1, wherein said exterior surface of said wall member is provided with a frictional coating.

ness, at least two longitudinally extending thin regions being separated by at least one longitudinally extending region of relatively greater thickness. 

1. In an apparatus having at least one gripper having a circumference, installed on a gripper carrier, for internally gripping a yarn carrier having an open interior defining an interior surface, which gripper includes a hollow element expandable under fluid pressure, and means for conducting fluid under pressure into the hollow element, the improvement comprising: a rigid downwardly extending wall member having an exterioR surface, which in an operative position is to contact the interior surface of the yarn carrier, said wall member forming part of said gripper and being fixedly connected to said gripper carrier and which, with said hollow element, can be introduced into the open interior of the yarn carrier, said exterior surface of said wall member forming a partial region of said circumference of said gripper and said hollow element being positioned adjacent said wall member, whereby upon expansion of the hollow member under fluid pressure the exterior surface of the wall member and at least portions of the hollow member may contact the interior surface of the yarn carrier.
 2. An arrangement as defined in claim 1, wherein said wall member extends downwardly for substantially the length of said gripper.
 3. An arrangement as defined in claim 1, wherein said wall member includes a lowermost portion which extends radially inwardly.
 4. An arrangement as defined in claim 3, wherein said lowermost portion of said wall member extends radially inwardly and downwardly.
 5. An arrangement as defined in claim 1, wherein said wall member subtends a central angle of from about 120* to about 180*.
 6. An arrangement as defined in claim 1, wherein said hollow member is a bag-like bellows, said wall member being disposed laterally adjacent said bellows.
 7. An arrangement as defined in claim 1, wherein said wall member is integrally connected to a flexible membrane and with said flexible membrane defines at least substantially said hollow element.
 8. An arrangement as defined in claim 1, wherein said exterior surface of said wall member is provided with a frictional coating.
 9. An arrangement as defined in claim 1, wherein said exterior surface of said wall member is provided with a coating of rubber.
 10. An arrangement as defined in claim 1, wherein said hollow element has a wall of non-uniform thickness, at least two longitudinally extending thin regions being separated by at least one longitudinally extending region of relatively greater thickness. 